Sewing thread



Oct. 1.9, 1943.Y 1 s, slMPsQN l 2,332,020

SEWING THREAD Filed Feb. 24, 1942 v jamw. Ums- SWFSC@ "His am cised toprevent the cotton Patented Oct. 19, 1943 unirse s'rrrllis'I PATENT'OFFICE .Hannes S. Simpson, Auburn, N.

Company, Auburn, N. Yan

ilolumbian- Rope Y., assigner to corporation ot New York .applicationFebruary 24. 1942, Serial No. d32,l67

(Cl. dif-155) This invention relates to an improved sewing ,threadespecially adapted for sewing paper bags,

There are various uses of paper .bags which make it highly desirablethat the entire bag, including its closure means, be readily dispersiblein water and paper pulp solutions. For instance. bags of sugar closed atthe ends by lines of stitches present dimculties under certaincircumstances if the thread is of cotton ber.` That is, particles of thecotton often become detached when the bag is being emptied vand fallinto the mixture in which the sugar is being used. This necessitatesadditional straining operations to remove such particles, because thecotton particles will not be dispersed. Again, if the contents yof thebag with a cotton thread closure are used in paper manufacture, caremust be exergetting into the paper pulp stock. rvA still furtherdisadvantage of the cotton thread closure is the reclaim value of thepaper bag for subsequent paper manufacture.

Paper bags sewn with cotton thread have a comparatively small reclaimvalue, this. ligure running from eight to fteen dollars a ton, due tothe necessity of using manual labor inremoving the cotton sewing thread,before the bag can be re-used in preparing pulp stock. For this reason,resort has been had to closing paper bags by pasting, but such a closureis too insecure for a large number of uses which require the safety andextra strength of sewing.

The primary object of the present invention, therefore, is to provide asewing thread particularly adapted for closing paper bags which can bedisposed together with the bag, as when reclaiming the bag in thepaper-making industry.

Another object is to provide a sewing thread capable of being readilydispersed in water, but which will possess suillcient flexibility andtensile strength to permit its use in commercial ma.- chines now usedfor sewing paper bags with vcotton thread.

Still another object is to provide a novel method of sewing paper bagswith a thread such as contemplated by the present-invention.

More specifically, the invention comprises a sewing thread made of paperpulp consisting essentially of a manila or hemp ber stock adulterated,if desired, by a small percentage of Wood ber stock, said threadpreferably being made of a plurality of plied ends, whereby thecomparatively low-tensile strength of the individual ends isvcompensated for by the plying of the ends.

In the accompanying drawing,

Figure 1 is a diagrammatical illustration of vbe prepared from manila ormechanism for twisting an end or thread; and iig. 2 similarlyillustrates a plying apparatus. In carrying out the preferred embodiment,of

the present invention, a pulp material is prepared and formed into paperaccording to the usual paper-making practices. This pulp may hemp :beronly, but'a small percentage of wood fiber may be used as the tensilestrength of the nished thread does not depend solely 'upon the inherentstrength of the paper used in its production. The paper thus produced isslit into strips approximately one-quarter inch in width and thesestrips twisted or spun into what, for convenience, are termed ends. Aplurality of these. ends are then plied together to `icrm the nishedend. In the usual practice in the present-day practices of manufacturingpaper from paper pulp stock.,-

a suitable sizing material is included inthe stock so that, when paperformed from the stock is calendered, the sizing will give a high surfacefinish to the paper. On the other hand, in carrying out the presentinvention, no sizing is used in the paper and calendering is minimized,all

contrary to normaLpaper manufacturing methods, as it is necessary thatthe nished thread 4possess a rather high degree of :flexibility in orderthat it can be used 'on the bag sewing machine andthe individualstitches formed without rupture of said thread. pulp stock will increasethe strength of the individual ends, it has been determined spinning ortwisting the ends rather ne and plying a number of these ends together,the tensile strength of the thread is materially in'- creased.Accordingly, it is thus possible to use as high as thirty or forty percent wood ber in the pulp stock. thus reducing costs, and still producea. paper thread that will stand up under the usages contemplated 'by thepresent invention.

In lieu of vegetable :ber paper ends, the invention, in its broadestaspect, can be practiced by forming said ends of certainwater-dispersible synthetic plastics. For instance, the ends may be madeof polyvinyl alcohol. As disclosed in an application led concurrentlyherewith by Gilbert R. Beebe and .Archie W. Koon, Serial No. 432,164,this material may be reduced to illm form and the latter cut into stripswhich are spun.or twisted to form the ends, all as is done with thepaper pulp stock. The thread may, it desired, also be. formed byextruding, the material in thread-like or iilamentary form.Plasticlzers, of

while an al1-manna aberv that, by

used to impart flexibility to the plied thread made from these ends andthe tensile strength may be increased by proper stretching of the threador ends composing the same.

Reverting to that embodiment of the invention in which the ends areproduced from a paper pulp stock, it is preferred that as large apercentage as possible of the fibersI oi the stock be arrangedunidirectional or lengthwise oi the web of paper into which the stock isielted. As previously stated, so far as concerns the tensile strength ofthe thread, spinning of the strips of paper into ends and the plying ofsaid ends to form the thread is relied upon or substituted for theadhesion oi hydrated fibers in the paper used in forming the thread.

It is also possible to increase the strength oi the plied paper threadby treating it or the ends during or after spinning with celluloseethers or esters or water-soluble. synthetic resins, such as thepolyvinyl alcohol previously referred to. Tests of plied paper threadsso treated show a material increase in the strength ot the thread.without an appreciable loss of flexibility.

A further ramication of the present invention lies in the application ofthe thread to the bag. The perfections in the sewing machines used forsewing paper bags have materially increased the speed of those machinesand it has been found that by moistening the present thread slightlybei'ore it passes through the eye of the sewing needle. the liability ofthe thread breaking is greatly reduced. This is due to the fact that themoistening not only increases theY flexibility of the all-paper thread,but it also lubricates the thread and minimizes irictional heat which isnormally generated during the sewing operation.

As previously indicated, the present invention has various advantages.Primarily, it more than trebles the reclaim value of the sewn bag. Papermanufacturers will pay a minimum price of thirty to thirty-five dollarsa ton for paper bags sewn with the present thread, compared with theminimum o! approximately ten dollars paid for the paper bag sewn withcotton thread. The use of the water-dispersible thread permits the bag,as reclaimed by the paper manufacturer, to be placed in the pulp beaterwithout any additional costs.- as compared with the necessity of usingmanual labor to remove cotton thread from bags sewn with thread of thattype. Again, numerous materials that are used in solutions in themanufacture ot products, where the presence of the paper bag indispersed form would not be detrimental but the presence of cotton iiberwould br. prohibited, can be shipped in bags using the present threadand used without emptying, it only being necessary to deposit the bag,ruptured or unruptured, in the container in which the solution isprepared. In any event, the use of the present thread absolutely'precludes contamination of any product by cotton iibers.

The steps of twisting and plying the thread or ends composing the threadare shown diagrammatically in the accompanying drawing. Fig. lillustrates a roll A of the material in strip form and the strip isdrawn over tensioning rods B, B, through a tube C on to a revolvingflyer or bobbin D which twists the strip into an end E. Where a numberof ends are used to form the thread, they are drawn through a tube F onto a revolving iiyer or bobbin G which twists them together into thethread T.

What I claim is:

l. A sewing thread consisting of a plurality of plied, unsized, paperends each composed essentially of a twisted paper pulp materialconsisting essentially of manila fiber pulp.

2. A sewing thread consisting of a plurality of unsized twisted paperends composed of manila ber pulp having wood fiber pulp mixed therewith,there being a preponderance oi manila ber pulp.

3. A paper bag closure formed by a sewing thread extending through thewall of said bag, said bag and thread both being dispersible in thebeater of paper-making apparatus under normal paper-making procedure.

4. A paper bag closure formed by a sewing thread extending through thewall of the bag, said thread being composed of a mixture of manila fiberpulp stock and wood ilber pulp stock, and said thread, together with thebag being dispersible under normal conditions in the beater ofpaper-makingapparatus.

5. A sewing thread consisting of a plurality oi 'ends of twisted,unsized paper each possessing a tensile strength, said endscomparatively low being plied to impart to the thread suiiicientstrength to be fed through a machine-operated sewing needle, said endsbeing formed of a paper gulp stock comprising wood ber and manila ber.

6. A water-dispersible thread for closing paper bags, said thread beingcomposed of a plurality of ends twisted together, each end being formedof a twisted strip of unsized, uncalendered paper pulp stock consistingessentially of manila fibers.

JAMES S. SIMPSON.

